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(11) | EP 0 213 686 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Lens and pattern holder |
| (57) A lens and pattern holder (1) for use with a grinding tool (3) comprising a rotary
grinding ring (5) mounted in coaxial relationship with respect to a guiding ring (7)
of the same diameter characterised in that the holder comprises:-
a) a solid body (31) having a pair of opposite surfaces (33, 35) spaced apart so that the peripheries thereof can be disposed respectively within the axial lengths of the grinding ring (5) and guiding ring (7); b) means on a first one (33) of the opposite surfaces of the body (31) for detachably connecting thereto a pattern (27) having a periphery outward from the periphery of the first surface, these connecting means consisting of two pins (30) spaced apart on the first surface and projecting therefrom for engagement with a pair of corresponding holes (41) provided in the pattern; c) means (47) on the other or second surface (35) of the body (31) for detachably mounting thereon a lens (29); and d) visual means on this second surface (35) for use as a guide to properly position and align the lens (29) with respect to the pattern (27) connected to the first surface (33) of the body (31) when mounting this lens on the second surface; whereby a finished lens (29) brought into edge contact with the guiding ring (7) serves as a guide for finishing the periphery of a pattern (27) pressed against the guiding ring (5) as the lens and pattern are rotated with the holder (1). |
[0001] This invention relates to a lens and pattern holder for use with a grinding tool to cut a pattern out of a demonstration lens generally provided with any new glasses frame or out of a "real" ophthalmic lens.
[0002] The invention also relates to a lens and pattern holder for use in cutting a lens from a pattern or to duplicate a pattern from another pattern.
[0003] It is common practice for the manufacturers of glasses frames to give a pattern to the optician with every new frame. This pattern is, in fact, a jig suitable to provide the general parameters necessary to cut a lens so that it fits in the frame. Usually, these parameters are the general axes of the lens and its outer contour.
[0004] A major problem encountered by the optician is to keep in store all the patterns necessary to satisfy his consumers' requirements; indeed, it can be easily understood that there is one given pattern for each frame. Since the number of frames that an optician must have held or holds in store is rather important, the number of patterns to be kept in store in order to be able to cut lenses fitting in existing or old frames is very important too and calls for a very well organized classification. Indeed, if a pattern corresponding to a given frame is lost and a customer wants the frame corresponding to this pattern for his new glasses or, alternatively, needs new lenses for his own frame corresponding to this lost pattern, the optician is obliged to contact the frame's manufacturer in order to obtain a new pattern, thereby substantially delaying the delivery of the new glasses to the customer.
[0005] In addition, it often happens that patterns supplied to the optician by some of the frame manufacturers are of very poor quality, thereby making their use difficult and/or impossible.
[0006] An object of the present invention is to provide a lens and pattern holder of very simple construction, which holder can be used with a very simple grinding tool to cut a new pattern that can subsequently be used for cutting an ophthalmic lens capable of fitting to a given frame using, as a guide, either a demonstration lens of the given frame or, in the case of a frame already used by a customer, from an ophthalmic lens supported by this frame.
[0007] Another object of the invention is to provide a lens and pattern holder which can alternatively be used for cutting an ophthalmic lens or cutting a blank pattern from an existing pattern in order to provide a lens capable to fitting in the frame corresponding to this pattern, or for duplicating an existing pattern.
[0008] A further object of the invention is to provide a lens and pattern holder which make it possible to cut ophthalmic lenses capable of fitting in a given frame in a very easy manner, such as polycarbonate lenses that require a dry grinding machine because they cannot be ground on conventional automatic edgers.
[0009] In accordance with the invention, these objects are achieved with a lens and pattern holder for use with a grinding tool comprising a rotary grinding ring mounted in a coaxial relationship with respect to a guiding ring of the same diameter, characterised in that the holder comprises:
a) a solid body having a pair of opposite surfaces spaced apart so that the peripheries thereof can be disposed respectively within the axial lengths of the grinding ring and guiding ring;
b) means on a first one of the opposite surfaces of the body for detachably connecting thereto a pattern having a periphery outward from the periphery of the first surface, these connecting means consisting of two pins spaced apart on the first surface and projecting therefrom for engagement with a pair of corresponding holes provided in the pattern;
c) means on the other or second surface of the body for detachably mounting thereon a lens; and
d) visual means on this second surface for use as a guide to properly position and align the lens with respect to the pattern connected to the first surface of the body when mounting this lens on the second surface.
[0010] In use, a finished lens mounted on the second surface of the body can be used as a guide for shaping and finishing the periphery of a pattern blank connected to the first surface of the body, such a shaping and finishing being obtained by pressing the finished lens and pattern blank against the guiding ring and the grinding ring, respectively, and rotating them with the holder. Alternatively, a finished pattern mounted on the first surface of the body can be used as a guide for shaping and finishing the edge of a lens, such a finishing being obtained by pressing the finished pattern and the lens against the guiding ring and the grinding ring, respectively, and rotating them with the holder.
[0011] In accordance with a first embodiment of the invention, the solid body has a main axis perpendicular or normal to its pair of opposite surfaces and the pins used for connecting the pattern on the first surface of the body are symmetrically positioned with respect to this main axis. The means for detachably mounting a lens onto the other surface of the body consists of a sticking pad, and the visual means for positioning and aligning the lens consists of three visible dots aligned on the second surface of the body, one of these dots being centrally positioned on the main axis of the body while the two other dots are symmetrically positioned with respect to this main axis close to the periphery of this second surface.
[0012] In order to provide a better support for the lens, the second surface of the body on which the lens is to be detachably mounted, can be slightly convex or slightly concave, depending on the nature of the lens.
[0013] In accordance with another embodiment of the invention especially intended for use to duplicate an existing pattern, the solid body has a main axis perpendicular or normal to its opposite surfaces and the pins used for connecting the pattern to the first surface are symmetrically positioned with respect to this main axis, and the means for detachably mounting a lens on the second surface of the body are, together with the visual means, replaced by another set of connecting pins similar to those projecting from the first surface, for detachably mounting another pattern instead of mounting a lens.
[0014] A non-restrictive description of three preferred embodiments of the invention will now be given with reference to the accompanying drawings in which:-
Figure 1 is a side elevation of a lens and pattern holder according to the invention for use in cutting a pattern from an existing lens, which holder is shown in use with a grinding apparatus;
Figure 2 is a perspective view of the holder shown in Figure 1;
Figure 3 is an enlarged, cross-sectional view of the holder and of the grinding tool shown in Figure 1;
Figures 4(a), (b), (c) and (d) are schematic representations of some steps to be followed when using the holder shown in Figures 1 to 3;
Figure 5 is a cross-sectional view of another holder for use in cutting a lens from a pattern;
Figure 6 is a cross-sectional view of a further holder for use in cutting a lens from an existing pattern; and
Figure 7 is a cross-sectional view of a knob for use with either of the holders of figures 5 and 6 to hold the pattern used as a guide.
[0015] The lens and pattern hold 1 shown in Figures 1 to 3 of the drawings, is intended to be used with a grinding tool 3 comprising a rotary grinding (or sanding) ring 5 mounted in coaxial relationship with respect to a guiding ring 7 of the same diameter. The grinding tool 3 can be mounted onto a shaft 9 driven by the small electrical motor (not shown) of an apparatus 13 provided with an upper flat working table 11 through which the shaft 9 extends.
[0016] As shown in greater detail in Figure 3, the grinding tool 3 comprises a drum 15 preferably made of brass, which drum is upwardly and coaxially extended with a ball-bearing mounted, cylindrical plastic top acting as the guiding ring 7. The bottom end of the drum 15 opposite to the plastic top 7 is provided with a central hole 17 to fit the shaft 9, and a small radially-extending set-screw 19 is provided for detachably fixing the drum on the shaft.
[0017] The bottom end of the drum 15 is shaped to receive and support an interchangeable grinding ring 5 having the same external diameter as the top 7. This ring 5, which can be made of brass with an outer covering of abrasive diamonds 25, can be held in position by means of a cap 21 and one or more cap screws 23. By way of example, the drum 15 may have a diameter of 25mm and a height of 33 mm, while the plastic top 7 may have a height of 15mm. Advantageously, the drum 15 is positioned on the shaft 9 so that the grinding ring 5 extends substantially about the level of the working table 11 of the apparatus 13, as clearly shown in Figures 1 and 3.
[0018] The lens and pattern holder 1 is intended to be used with the grinding tool 3 for cutting a pattern 27 from a demonstration or ophthalmic lens 29. More particularly, the holder 1 is intended to be used with the tool 3 for shaping and finishing the periphery of a blank pattern 27 using the edge of the lens 29 as a guide, in order to subsequently use this pattern for the manufacture of another lens capable of fitting the frame of the glasses from which comes the lens 29.
[0019] As best shown by Figure 2 and 3, the holder 1 comprises a solid body 31 having a pair of opposite surfaces 33 and 35 spaced apart so that the peripheries thereof can be disposed respectively within the axial lengths of the grinding ring 5 and the guiding ring 7 when the holder 1 is used for cutting a pattern 27 from a lens 29. The body 31 has a main axis 37 perpendicular or normal to its opposite surfaces 33 and 35, and comprises means at its lower or first surface 33 (which is flat) for detachably connecting thereto the pattern 27 to be cut, such cutting making it compulsory that the pattern 27 must have a periphery outward from the periphery of the surface 33 of the body 31.
[0020] As clearly shown in Figure 2 means for connecting the pattern 27 consists of two spaced apart pins 39 projecting from the surface 33 to engage a pair of corresponding holes 41 provided in the pattern blank to be cut (see Figure 4(b)). The pins 39 are symmetrically positioned with respect to the main axis 37. In this connection, it should be noted that the use of flat patterns or pattern blanks provided with fitting holes 41 is standard practice in this field. By way of example, reference can be made to the flat patterns that are conventionally used with the automatic edgers provided with a SHURRON attachment, which patterns comprise two positioning holes having a diameter of 2mm, the distance between the centres of these holes being 16mm.
[0021] In order to make the manipulation of the holder easier, the body 31 may have two flat sides 43 (see Figure 4(c)) extending parallel to the plate 45 passing through the axes of the pins 39 (see Figure 4(d)).
[0022] Means are provided on the other upper or second surface 35 of the body 31 for detachably mounting thereon the lens 29. These means for detachably mounting the lens 29 may consist of a sticking pad 47 like the one sold to opticians by the 3M company under the tradename LEAP PAD. The surface 35 is advantageously convex. This convexity may be, for example, of 6 diopters to fit most ophthalmic lenses. In addition, to the pad 47, the upper surface 35 of the holder body 31 is provided with visual means for use as a guide to properly position and align the lens 29 with respect to the pattern 27 connected to the lower surface 33 when mounting the lens onto the upper surf ace 35. As shown in Figures 2 and 3, these visual means preferably consist of three coloured dots 49, 51 and 53 which are aligned so as to lie in a plane passing through the axes 37 and 45. The dot 51 is centrally positioned on the main axis 37 of the body so as to be visible through a generally central hole provided in the sticking pad 47. The other dots 49 and 53 are symmetrically positioned with respect to the main axis 37 close to the periphery of the surface 35.
[0023] The holder 1 can be made of plastic material such as DELRIN (trademark). It may have a diameter of 38 mm and a height of 32 mm so as to align appropriately with the rings 5 and 7 of the grinding tool 3. In the case where the body has two lateral flat sides 43, the distance between these flat sides may be 32mm.
[0025] First of all, the lens 29 intended to be used as a guide for cutting the pattern 27 is positioned with the frame of the glasses to which it belongs, into a lensometer. The three dots of the lensometer are then aligned with respect to the lens so that they can be marked on the lens equidistant from the top and bottom edges and symmetrically disposed with respect to the side and nasal edges of the lens 29, respectively (see fig. 4(a)). The lens 29 is then removed from the frame and a line 55 drawn to join the small dots made with the lensometer. A line 57 is also drawn perpendicularly to the line 55 in the middle thereof (see Figure 4(a)). To draw these lines, use can be made of a fine permanent black ink such as the one sold under the tradename STAEDLER LUMO COLOUR 313.
[0026] Subsequently, the cross defined by the lines 55 and 57 is aligned with the pin receiving holes 41 of the pattern blank 27 to be cut (see Figure 4(b)). The point of intersection of the lines 55 and 57 must, during this step, be positioned midway between the holes 41, where there is usually a large central hole 59 in most of the presently available pattern blanks. After this lining up, a fine line is traced around the lens 29 using a pen 61 (see Figure 4(b)), while the lens is firmly held in place. Then, the pattern blank 27 is cut with scissors following the traced line in order to roughly define the general contour of the patern to be cut.
[0027] A sticking pad 47 is applied to the convex surface 35 of the holder 1 in such a manner as not to cover the dots 49, 51 and 53. The cross defined by the line 55 and 57 on the lens 29 is lined up with the dots 49, 51 and 53 on the upper surface 35 of the body 31 thus providing a visual means for properly positioning the lens 29 on the pad 47 with respect to the holder 1 (see Figure 4(c)). In a further step, the precut blank pattern 27 is installed on the pins 39 projecting outwardly from the lower surface 33 of the body 31. During this operation, it is important to check that the top and nasal sides of the lens and pattern are correspondingly aligned (c.f. Figures 4(c) and 4(d)).
[0028] Then, the holder assembly is ready to make a pattern identical to the lens 29. To do so, the holder 1 with the pattern 27 and the lens 29 connected thereto is placed on the working table 11(as shown in Figure 3) and, while applying vertical pressure on it, the holder is moved towards the grinding tool 3 while the same is rotated. When contact is made between the pattern 27 and the diamond abrasives 25 on the ring 5 (see Figure 1) the assembly is rotated in a direction opposite to the direction of rotation of the ring 5 until the pattern 27 is properly finished.
[0029] Tests conducted by the inventor have shown better results are achieved by going around a lens twice. The first rough turn must be made without stopping the grinding tool 3 from rotating. The second finishing turn can be made with more pressure.
[0030] As can be easily understood, the grinding ring 5 will grind the rough pattern 27 until the lens reaches the guiding ring 7, which is free to rotate about its ball-bearing. This guiding ring 7 then will not allow more cutting than the actual size of the lens, thereby making the operation extremely simple and efficient.
[0031] In accordance with another embodiment of the invention shown in Figure 5, the holder 1' is intended to be used for cutting a lens from a pattern. In this particular case, the lens receiving surface 35' is now lowermost and is concave instead of being convex so that only the edge of the lens to be cut will be in contact with the working table 11. The surface 35' is also provided with coloured dots 49', 51' and 53' for use to position and align the lens to be cut with the pattern. The concavity of the surface 35' can be of 6 diopters, for the same reason as above. The other and now upper surface 33' of the holder 1' is provided with two pins 39' for use to fix the pattern acting as a guide for cutting the lens. A threaded blind hole 63' may be provided in the body 31' to receive the screw 65 of a small knob 67, as shown in Figure 7, the main purpose of which knob is to firmly hold the pattern on top of the holder 1'. The threaded hole 63' and the screw 65 are preferably positioned coaxial with the main axis (37) of the body 31' to match with the central hole 59 generally provided in most of the commonly available blanks 27.
[0032] The holder 1' can be used substantially as described hereinabove with respect to the holder 1, except that, in this particular case, the pattern 27 comes into contact with the guiding ring 7 when the lens 29 to be cut is pressed against the diamond abrasives 25 of the grinding ring 5.
[0033] In a third embodiment of the invention shown in Figure 6, the holder 1" is intended to be used for cutting a pattern from another pattern. The upper surface 33" of the body 31" of this holder 1" is substantially identical to the upper surface 33' of the holder 1' in having a pair of pins 39" and a central hole 63" for use to mount the pattern used as a guide. However, the means used for detachably mounting a lens on the surface 35 or 35' of the body are, together with the visual means used for aligning this lens, replaced by a set of connecting pins 69" aligned with the pins 39", which pins 69" project downwardly from the flat lower surface 35" for mounting another pattern to be cut instead of mounting a lens.
a) a solid body (31) having a pair of opposite surfaces (33, 35) spaced apart so that the peripheries thereof can be disposed respectively within the axial lengths of the grinding ring (5) and guiding ring (7);
b) means on a first one (33) of the opposite surfaces of the body (31) for detachably connecting thereto a pattern (27) having a periphery outward from the periphery of the first surface, these connecting means consisting of two pins (30) spaced apart on the first surface and projecting therefrom for engagement with a pair of corresponding holes (41) provided in the pattern;
c) means (47) on the other or second surface (35) of the body (31) for detachably mounting thereon a lens (29); and
d) visual means on this second surface (35) for use as a guide to properly position and align the lens (29) with respect to the pattern (27) connected to the first surface (33) of the body ( 31) when mounting this lens on the second surface.
a) the solid body (31) has a main axis (37) perpendicular or normal to its pair of opposite surfaces (33, 35);
b) the pins (39) used for connecting the pattern (27) on the first surface (33) are symmetrically positioned with respect to the main axis (37);
c) the means for detachably mounting a lens (29) on the second surface (35) of the body (31) consists of a sticking pad (47); and
d) the visual means for positioning and aligning the lens (29) consist of three visible dots (49, 51, 53) aligned on the second surface (35) of the body (31), one of the dots (57) being centrally positioned on the main axis (37) of the body (31) while the two other dots (49, 53) are symmetrically positioned with respect to said main axis close to the periphery of the second surface.
a) the solid body (31") has a main axis (37) perpendicular to its pair of opposite surfaces (33" and 35");
b) the pins (39") used for connecting the pattern (27) on the first surface (33") are symmetrically positioned with respect to the main axis (37);
c) a threaded blind hole (63") extends coaxial with the main axis (37) of the body (31") from the first surface (33") thereof, for receiving the screw (65) of a knob (67) for holding the pattern (27) firmly; and
d) the means for detachably mounting a lens on the other surface of the body are, together with said visual means, replaced by a set of connecting pins (69") projecting from the second surface (35") and similar to those projecting from the first surface (33") for detachably mounting another pattern instead of mounting a lens.